THE PERFORMANCE OF THE ALL-DIGITAL DATA TRANSITION TRACKING LOOP USING NONLINEAR-ANALYSIS

This paper describes the performance of the all-digital data transitio n tracking loop (DTTL) with coherent and noncoherent sampling using no nlinear theory. The effects of few samples per symbol and of non-comme nsurate sampling symbol rates are addressed and analyzed for perfectly square pulses as well as Altered pulses. Their impact on the probabil ity density and variance of the phase error are quantified through com puter simulations. It is shown that the performance of the all-digital DTTL approaches its analog counterpart when the sampling and symbol r ates are noncommensurate (i.e., the number of samples per symbol is ir rational). The phase error variance for an even number of samples per symbol is also shown to degrade compared to an odd number of samples p er symbol.